The invention relates to improvements in devices for connecting in tight, sealing relationship to two rigid parallel perforated plates with the ends of tubes of glass or a similar material forming part of a bundle of parallel vertical or inclined tubes making up a heat exchanger.
The invention relates more particularly to devices which comprise a resilient ring for connecting each tube end with the edge of a hole in a plate.
According to the invention, if d denotes the inside diameter of the tube, D its outside diameter and t the diameter of the hole, the diameter t is equal or substantially equal to D and the ring has in axial half-section the general shape of a flattened Z, such ring being made up of two cylindrical sleeves which partly enclose one another and are offset axially in relation to one another, the first sleeve having an inside diameter d and an outside diameter t and being adapted to penetrate joiningly into the hole and to axially abut the tube end, while the second sleeve has an inside diameter D and is adapted to enclose joiningly such tube end and to rest axially against the edge of the hole.
An assembly of this kind eliminates the risk that, if the lower connecting ring of a tube to the lower plate is damaged or destroyed, such tube drops through the hole facing such plate, which risk appeared with the prior art assemblies, causing many inconveniences: with the assembly of the invention, even if only small pieces of the lower ring remain in place, they are enough to prevent the free passage of the tube through the hole, the radial clearance required for such passage being insufficient.
In preferred embodiments one and/or the other of the following arrangements are used: the two sleeves are moulded in a single unit; the two sleeves making up the same ring are inserted in one another and made of different materials, the first sleeve being inter alia formed by an asbestos jacket; the second sleeves of the rings connecting adjacent tube ends to the same plate bear laterally against one another; the two plates are strutted by rigid bars, preferably four bars, with the interposition of resilient washers between the bars and at least one of the two plates.
Apart from these main arrangements, the invention comprises certain other arrangements which are preferably used simultaneously and will be more explicitly described hereinafter.